Manufacture of flexible abrasive articles



Feb. 15, 1938. R c. BRYANT MANUFACTURE OF FLEXIBLE ABRASIVE ARTICLES 4 Sheets-Sheet 1 Filed March 18, 1933 INVENTOR. ED658763 .58721/17'1 BY A TYI'ORNEY Feb. 15, 1938.

R. c. BRYANT 2,108,645 MANUFACTURE OF FLEXIBLE ABRASIVE ARTICLES Filed March 18, 1933 Sheets-Sheet 2 A TTORNEY Feb. 15, 1938.

R. c. BRYANT 2,108,645 MANUFACTURE OF FLEXIBLE ABRASIVE ARTICLES Filed March 18, 1933 4 Sheets-Sheet 5 INVENTOR. @0652 c .5E7A/Y7T BY a h A TT ORNE Y Feb. 15,1938' R. c. BRYANT MANUFKCTURE' 0F FLEXIBLE ABRASIVE ARTICLES Filed March 18, 1933 4 Sheets-Sheet 4 JNVENTOR.

ATTORNEY Patented Fella llfi lgfi v v nnir stares e rant EAWWMS MANHWAQTURIE 01F AERASHVE AETHQLES Robert if). Bryant, Niagara Falls, N. lL, assigimor,

by mesne assignments, to The fillarbornndnm Company, Niagara Falls, N. EL, a ccrperation of Delaware Application March 18, M33, Serial No, diilhfifiti e Claims (Cl. ill-68) This invention relates to the manufacture of My improved method of manufacture of interflexible abrasive articles with intermittent or mittently coated abrasive fabric is illustrated by discontinuous coatings and relates particularly the accompanying drawings in which:

to improved methods of producing such flexi- Figure 1 shows in elevation apparatus for proble abrasive articles with intermittent coatings of viding fabric with an intermittent coating of admore definite pattern and of more uniform charhesive and a subsequent coating of abrasive; acter than is provided by present commercial Figure 1A is a fragmentary view showing a porpractice. tion of the peripheral surface of the embossed The article which it is desired to produce by or engraved roll in Figure 1;

my improved methods should be distinguished Figure 2 shows a modification of the appara- 10 from open-coated abrasive articles in which tus shown in Figure l, in which modification the abrasive grain is distributed on an adhesively fabric is first given a uniform coating of adhecoated backing in such a manner that the spaces sive which is subsequently made discontinuous; between the abrasive granules are comparatively Figure 3 shows a modification of the apparalarge as compared with the ordinary close-coated tus indicated in Figure 1 i ns om he at- 15 abrasive fabric. In my improved flexible abrater in that the liuqid adhesive is transported to sive articles there are areas of coated abrasive the fabric by means of an engraved or embossed with interspersed areas which are slightly coated T011 instead of a Smooth roll; with abrasive or which are substantially uncoated Figure 4i shows coating apparatus diflering m with abrasive grain. As compared with the orfrom that indicated in Figure 3 in that t e en- 2 dinary open-coated flexible abrasive articles the crav d r i supp d w th adh s v fr m a more densely coated abrasiv areas of my l smooth roll which contactswith the main supply proved article are more resistant to the shearing of adhesive; stresses exerted by the work than are the indi- Figure 5 shows coating apparatus difiering 5 vidually supported abrasive granules of the. ordifrom that indicated in F ew-" 3 by e u e f a nary open-coated abrasive fabric. The inter- Supplementary roll which impresses & Second a spersed open areas in my improved abrasive fabric hesive pattern on the fabric;

are useful in preventing the accumulation of s fish ws in elevation apparatus for p tdebris in the denser abrasive areas of the abranc d s v lv coated a r w t a patt rn 0 sive fabric. As compared with open-coated abraformed 0f abrasive grain;

sive fabric the type of abrasive fabric to which gu e d fi s f om F e 6 in the substituthis invention relates may be called intermittentllioh 0f e belt for Carrying abrasive grain i to ly or discontinuously coated abrasive fabric. Contact w the fabric;

According to the present invention, the open- Figure 8 illustrat s appa us d f n fr m coated effect is obtained by a change in the that Of Figure h the addition of pp ry 35 method of putting the adhesive on a travelling means to prevent Coating 0f certain 13011110115 of fabric, in contrast to the methods which have the fabric With abrasive grain; and been previously employed for an analogous pur- Figure 9 illustrates method of app yin a pose, such as changing the unt of grain controlled quantity of adhesive to a sheet in a M jected on the travelling fabric per unit time or Pattern which is late! smoothed Out o a coating 40 changing the speed of the travelling fabric. of substantially uniform thickness by means of As an example of a type of method which has a brushbeen used to form intermittently coated abrasive Referring to the drawings in detail, the T011 2 fabric, an adhesively coated sheet of fabric has in Figure 1 contains a pp y of P p 010th been passed under a hopper from which abrasive t0 be i The material to be coated is granules fall in a thin sheet, while a perforated er ed to generally i th s pp n fabric. mask permits abrasive granules to fall on certain The fabric is d aw between a p of rotating portions only of the travelling sheet. With such rolls 3 and 4. The rotatin has SmOOth apparatus, the tendency is to form heaps of mulsurface which receives a film of liquid adhesive ti-layered abrasive under the perforations in the from a supply 5. The roll 3 is provided with a mask. Thick coatings of sizing are needed to pattern, depressed portions of which are shown hold the upper layers of abrasive. The abrasive at I in Fig. 1. As the fabric passes between the article thus formed is stiff and does not have rolls 3 and 4, liquid adhesive is trhnsferred to the the flexibility desirable in intermittently coated lower side of the fabric but not in a uniform abmSWe fabricv coating. The outer portions 6 of the roll 3 press .dips in the lowest part of its out the adhesive from those portions of the fabric surface which lie opposite to said outer portions 6 of the roll 3. Portions of the fabric surface which come opposite depression 1 (as they pass between the rolls 3 and 4) will receive adhesive from the smooth surface of the roll 4. The fabric'receives, therefore, areas of liquid adhesive whose outlines correspond to those of the depressions 1 indicated in Figure 1A. The areas corresponding to the continuous areas 6 (indicated in Figure 1A) have only a small thickness of liquid adhesive on account of the pressure exerted by the projections 6 during the coating interval. After passing between the rolls 3 and 4 the coated side of the fabric is brought above the uncoated side by means of the rolls 8 and 9 so that abrasive grain can be dropped on it from a hopper II. A rotating member l2 positioned at the outlet of the hopper releases the grain in a falling sheet which impacts on the travelling fabric. The coated fabric is brought into a vertical plane as it passes the roll l3. Grain that has fallen on the areas thickly coated with adhesive is largely retained, while grain that has fallen on the areas which are very thinly coated with adhesive falls off to a large extent, this action being assisted by the beater l4 which helps to remove the granules which are more lightly held. The intermittent character of the abrasive coating thus obtained is indicated in the portion of the fabric that has passed the roll l3 in a downward direction in Fig. 1. The fabric then passes to a drier in which the liquid adhesive is hardened. A- sizing coating of adhesive can be given subsequently to reinforce the attachment of the abrasive grain to the fabric.

The apparatus shown in Figure 2 is similar to that shown in Figure 1 except that the fabric receives a coating of liquid adhesive on its passage between smooth rolls 3' and 4' the latter of which travel into a vessel containing liquid adhesive. The travelling fabric thus receives a comparatively uniform coating of adhesive on its lower side. This coating of adhesive is shortly thereafter the passage of the fabric between the smooth roll l6 and the embossed or engraved roll [5. In the abrasive-coated article finally obtained, the intermittent coating depends on the character of raised surface of the roll IS. The raised portions H of this roll produce bare spots on the flexible abrasive article and the depressions I8 on the other hand produce abrasive-covered areas.

The apparatus shown in Figure 3 is similar to that shown in Figure 1 except that the lower roll of the pattern-forming pair is engraved instead of the upper roll. The depressions l9 produce abrasive-coated areas in the resultant product and the raised portions M produce bare spaces in the resultant product? The fabric is printed with a glue pattern in a manner somewhat analoous to the process used in engraved printing. In the latter process however, the paper surface receives no ink, outside of the printed letters. In the applicant's process liquid adhesive is squeezed from some portions of the surface of the fabric on to other portions. A scraper 22 can be used to regulate the thickness of the coating of adhesive more particularly on the raised portions of the engraved roll.

The apparatus illustrated in Figure 4 differs from that illustrated in Figure 3in that the roll which transports liquid adhesive to the fabric does not dip into a container which holds a supply of liquid adhesive. The smooth roll 23 takes admade non-uniform by V to the raised portions hesive from the container during its rotation and transfers it to the engraved roll 4" which in turn transmits adhesive to the fabric.

The apparatus illustrated in Figure 5 is similar to that illustrated in Figure 3 as far as the impression of the primary adhesive pattern is concerned. An additional roll 24 having a second pattern is used to press adhesive from other areas on the fabric. 4" which dips in the liquid adhesive is provided with parallel raised portions while the roll 24 is provided with other parallel raised portions which cut across the primary adhesive pattern which has just'been formed and form a secondary adhesive pattern.

In the apparatus shown in Figure 6, the travelling fabric receives a coating of adhesive on one side from the rotating roll 25 acting in conjunc tion with the dry counter or calender roll 26. The adhesive coating thus received by the fabric is comparatively uniform in thickness. This uniformity is enhanced by the action of the brush 30. The fabric then passes between a smooth roll 21 and a rotating member 28 which carries a series of pockets 29. As these pockets near their uppermost positions they are supplied with abrasive from a hopper 3|. The heaps of abrasive grain received from the hopper into the pockets are reduced to the desired extent by means of a scraper 32. The abrasive grain in the pocket which has just been levelled comes next into contact with the fabric under the center of the roll 21. The fabric thus becomes intermittently coated in accordance with the distribution of pockets on the rotating member 28. The abrasive-coated fabric then passes on to the drier where the adhesive is hardened. As the pocket 29 continues its rotation from its highestposi tion it is cleared of abrasive by the action of gravity. The falling grain is received in a container 33 and is removed by a rotating screw member 34 or by a travelling belt and retained for further use.

The apparatus illustrated in Figure '7 is similar to that illustrated in Figure 6 except that a travelling belt'36 takes the place of the rotating member 28. With the apparatus shown in Figure 7 it is possible to fill the pockets 29 to a higher level with abrasive since the belt travels horizontally from the hopper to the contact with the roll 21.

The apparatus illustrated in Fig. 8 is similar to that illustrated in Figure 3 except that further provision is made to prevent abrasive grain from sticking to portions of the fabric which it is desired to keep free from grain. This furtherprovision is to be found in the engraved roll 36 and the smooth roll 31 which last-mentioned roll transports talcum powder from a container 38 of the roll 36. The roll 36 is provided with a pattern of raised parts and depressions which correspond closely to those on the roll 4". 36 is'timed so that talcum is deposited on those portions of the fabric from which adhesive has been pressed by the roll 4". When the adhesively coated fabric comes under the hopper I I the grain which falls on the talcum coated areas is easily removed after it passes the roll 4| by gravity and the action of the beater I4.

My improved intermittently coated abrasive fabric has many advantages. The need for flexible abrasive fabric is shown by the attempts which have been made to produce flexible abrasive fabric by bending it successively over rods For example, the engraved roll,

The driving apparatus for the roll success or bars of small diameter. This procedure breaks the binder along a series of parallel lines. These flexing operations weaken the adhesive layer and often cause peeling. This is especially the case with heavy abrasive materials such as floor-sanding abrasive fabric. With my improved intermittently coated abrasive fabric it it not necessary to resort to these flexing operations if suitable patterns are used on the embossed rolls which I have disclosed and if. the thickness and'viscosity of the adhesive coating are properly regulated.

Instead of square or rectangular abrasive areas I can use diamond-shaped abrasive areas which have the general form of a rhombus, the long diagonal of the rhombus making an angle of 25- 30 with a side of the rhombus. Abrasive fabric having abrasive areas of this type is naturally flexible along the bare channels that separate the abrasive areas.

Any suitable driving means may be used for rotating the various rolls and the fabric in contact therewith. A series of electric motors whose speed can be changed in unison or individually is desirable fur this purpose. Some of the rolls whose purpose is to change the direction of. the fabric can be mounted to turn freelyi around their supporting shafts while the latter are mounted in slots in a resilient manner so that lateral motion of the shafts is possible. in this manner sudden strains in the fabric are reduced. Suction drums are used in contact with the fabric where they are necessary for facilitating continuous regular movement of the fabric. in the case of the opposed rolls, such as be the driving member while the other roll is mounted to rotate freely on its supporting shaft or both rolls can be rotated in. opposite directions by synchronous driving means.

The apparatus indicated in Figure Q may be used to control the quantity of. adhesive which is applied to a given area of fabric. This quantity is varied, for example, by varying the depth and the-area of the recesses iii. Adhesive is scraped from the raised portions of the roll 5" by means of the scraper 22. The use of this scraper is however optional. The fabric is printed with the adhesive pattern of controlled thickness as it passes between the rolls t" and d. The fabric with its intermittent coating of adhesive is subjected shortly thereafter to the action of a brush 39 which smooths out the adhesive coating so that it becomes substantially uniform in thickness. This uniform coating of adhesive can then be given a coating of abrasive which is held to the fabric by means of a moreuniform coating of adhesive than is ordinarily obtainable. The importance of this result lies in the fact that customers frequently request abrasive fabric of a grade similar to that which they have purchased on a previous occasion. By using similar paper an adhesive together with an engraved (or embossed) roll of the same character that was used in producing the preferred product, duplication of. this desired product is made possible.

Again by giving the embossed roll GB" in Figure 3 or in Figure 9) a pattern with a small mesh, that is, a pattern with small depressed areas, I am able to obtain an adhesive pattern of correspondingly small adhesive areas on the fabric. The dots of adhesive retain one or more coarse abrasive grains such as 16 grit, the area of the adhesive being only large enough to retain a very small number of granules. The

not become 3 and ti, either roll can sive granules on raised portions of the engraved roll can be made of such dimensions that the distances between the little islands of abrasive are large or small. In this way I am able to make abrasive sheets having a controlled open coating. Such sheets have superior abrasive qualities since they do clogged so readily with the debris which results from abrasive operations.

The rolls having irregular surfaces can be made by various methods such as engraving, embossing, knurling, attaching strips of various materials to the surface of the roll or any other feasible means by which a patterned roll can be constructed. I do not wish to limit myself to any particular material in the construction of the roll.

The shape of the adhesive patches can be controlled by varying the shapes, sizes and depths of the depressions in the engraved or embossed roll. For example, one side of the pocket may be deeper than the other. The pockets may differ among themselves in depth and contour, so that the patches of adhesive on. the fabric can be made to vary among themselves according to a predetermined pattern.

In the manufacture of abrasive disks by a method involving the apparatus described above only the portions which are to be cut out need to be coated with omy in the adhesive and abrasive used.

' "While my improved apparatus can be embodied in various ways my invention is described within the compass of the following claims.

I claim:

1. The method of manufacturing intermittent- 1y coated abrasive fabric which comprises giving one surface of the fabric a substantially uniform coating of adhesive, then squeezing the adhesive from portions of said surface which it is desired to have free from abrasive, then projecting abrasive grain onto the surface thus intermittently coated with adhesive, and thereafter hardening the adhesive.

2. The method of manufacturing intermittently coated abrasive fabric which comprises applying a thin coating of liquid adhesive to one face of a fabric, then after a short interval pressing out the adhesive from certain areas in a pattern which is indefinitely repeated on the surface of the fabric, dropping finely divided abrasive on the unevenly coated adhesive surface, and removing abrasive particles from the less adhesive portions of the surface thus treated.

3. The method of manufacturing intermittently coated abrasive fabric which comprises applying a thin coating of liquid adhesive to one face of a fabric, then after a short interval pressing out of parallel fabric and adhesive along a plurality of series strips, said strips extending across the the strips of one series intersecting the strips of any other series, then dropping finely divided abrasive on the unevenly coated adhesive surface, and removing abrasive particles from the less ad hesive portions of the surface thus treated.

4. The steps in the. method of making a flexible abrasive coated article having distributed abrasive and non-abrasive areas which comprise applying adhesive to one side of a fabric and simultaneously impressing the opposite side of said fabric with localized pressures to form a pat terned adhesive coating, and distributing abrathe patterned side of the fabric.

5. The steps in the method of making a flexible abrasive coated article having regularly distributed abrasive and non-abrasive areas which comprise applying adhesive to one side of a fabric adhesive, thus effecting econ and simultaneously impressing the opposite side of the fabric with localized pressures applied toward the areas which are to be non-abrasive, and distributing abrasive granules on the patterned side of the fabric.

6. The steps in the method of making a flexible abrasive coated article having distributed abrasive and non-abrasive areas, which steps comprise passing a web so that the surface elements of one side of the web contact successively with a source of adhesive supply on a rotating cylinder and subjecting the web to localized pressures produced by an engraved cylinder that presses partly of the web against the adhesives coated cylinder and which leave said side of the web coated with a pattern of adhesive in substantially the same fluid condition as the adhesive supplied, distributing abrasive particles over the side of the web that has the adhesive pattern, hardening the adhesive, and removing abrasive from the portions of the web which have been subjected to localized pressures and to which the abrasive particles are consequently not strongly attached.

7. The steps in the method of making flexible articles intermittently coated with abrasive grains which comprise apply g adhesive to the surface of the fabric to be coated with abrasive grains, pressing the adhesive away from predetermined portions of said surface by localized pressure applied to the surface of the fabric opposite to that which is to be coated with abrasive grain at points corresponding to those at which the abrasive coating is to be interrupted, and distributing abrasive particles on the side of the fabric that has been intermittently coated with adhesive.

8. In the method of making flexible articles intermittently coated abrasive particles and produced by the formation of an adhesive pattern on a traveling web with subsequent distribution of abrasive particles on the same side of the web followed by removal of excess abrasive and the hardening of the adhesive, the step of pressing the adhesive away from predetermined portions of said surface by localized pressure applied to the surface of the fabric opposite to that which is to be coated with abrasive grain at points corresponding to those at which the abrasive coating is to be interrupted.

- ROBERT C. BRYANT.

with binder and attached 

